1.9tdi AWX loss of throttle

[morticiaskeeper]

A VERY intermittent problem. Throttle fails to respond, come totally off the pedal, then control returns. ESP light comes on, usually goes off when up to speed, but sometimes stays on until shutdown. Fuel consumption and performance have not changed. It usually happens when coming out of a car park or other slow speed stuff.

Engine ECU fault codes are:

18039/P1631 - Accelerator Position Sensor (G79): Signal too High
17553/P1145 - Mass Air Flow Sensor (G70): Short to Plus

Pedal has been replaced.

Hair now being torn out!

[Crasher]

This is usually water damage to the ECU.

[morticiaskeeper]

Today it got worse. Thirty miles on the motorway with no problems. Back on the A roads and it was terrible. Limped to my mums house and called the AA.

He read the same faults as me and suggested it was either the MAF or the pedal!

Limped home with him following. Swapped the pedal back to the old one, still the same faults. Cancelled holiday.

Disconnected the MAF, the only fault code showing is:

17552/p1144. Mass air flow [MAF] sensor-670pen/short to ground

But, it's drive able, a bit dull but still better than the Ibiza 1.2. No warning lights on.

New MAF on Monday.

Edited to add: no indications of water near the ECU.

[morticiaskeeper]

New Bosch MAF fitted, fault codes cleared.

GPS derived HP was 60 previously, now it's 114. Plenty of towing tests to give it a load, but it's looking good.

[morticiaskeeper]

New Bosch MAF fitted, fault codes cleared.

GPS derived HP was 60 previously, now it's 114. Plenty of towing tests to give it a load, but it's looking good.

Update.

A thousand miles later, the throttle went again. Fault code said position sensor. Steadily got worse, so changed the pedal, still bad. Only got home from holiday with the cruise control.

Struggled to reverse onto drive, glow plug lights showing, MAF fault code appears again, as does a low voltage code which then disappears.

Chasing a possible earthing problem now, and scouring the ads for a reliable day van!

[Crasher]

Have you checked the ECU plug and pins for water damage?

[morticiaskeeper]

Have you checked the ECU plug and pins for water damage?

No signs of water damage in the ECU box, but I will revisit it.

The MAF & Pedal share an earthing loom, so I'm going to investigate that tomorrow night.

[Crasher]

Unplug the ECU and check the pins for corrosion.

[morticiaskeeper]

Watched the throttle position reading fluctuate last night. Also had a voltage warning on the pedal.

I spoke to a customer of mine today and they are going to take a look on Thursday.

It started doing this just after the big snows in March, further pointing to contacts.

[morticiaskeeper]

All connections seem good, but the ecu has a burning smell behind the smaller connector :-(

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